(a) Field of the Invention
The present invention relates to a control apparatus of a fuel cell vehicle and a control method thereof. More particularly, the present invention relates to a control apparatus of a fuel cell vehicle having a plurality of driving systems and a control method thereof.
(b) Description of the Related Art
A fuel cell is an electric generator system for transforming chemical energy to electrical energy, wherein unit cells having a pair of an anode and a cathode between electrolytes are arranged in series.
A balance of plant (BOP) is used to supply the anode of the unit cell with hydrogen and to supply the cathode with oxygen such that electricity and heat are generated through chemical reaction of an ionized material.
FIG. 6 shows a power net of a conventional fuel cell vehicle, which includes a fuel cell stack 100, a super capacitor 120, an inverter 130, a motor 140, a reduction gear unit (RGU) 150, and a gear differential unit (GDU) 160.
The fuel cell stack 100 as a main power source generates electricity through a chemical reaction of hydrogen supplied to the anode with oxygen supplied to the cathode of the unit cell through the BOP.
The super capacitor 120 is an assistant power source that can be quickly charged and discharged, is connected to a power line 102 in parallel to assist output power of the fuel cell stack 100, and charges regenerative braking energy to improve efficiency of the fuel cell.
The inverter 130 includes an insulated gate bipolar transistor (IGBT) as a semiconductor element, and transforms DC high voltage outputted from the fuel cell stack 100 and the super capacitor 120 through high speed switching so as to operate the motor 140.
Output torque of the motor 140 is increased by the RGU 150 as a first reduction gear, and is increased by the GDU 160 as a second reduction gear to be transferred to a wheel.
In the conventional fuel cell vehicle, one fuel cell and one motor are used. Accordingly, the top speed of the vehicle is relatively low and driving performance is not excellent on an uphill road.
A multi-driving system has been introduced to offer high torque, in which a plurality of motors are connected in parallel, and inverters for operating each motor are disposed therein.
As shown in FIG. 5, the multi-driving system generally includes three motors, and a power coupling device (PCD) that is engaged with gears connected to rotation shafts of the motors to transfer driving torque with one shaft.
However, in the multi-driving system, different torques are applied to each input shaft A of the PCU operated by each motor such that durability of reduction gears is deteriorated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.